1. Field of the Invention
The present invention relates to a wireless communication network. More particularly, the present invention relates to a method and apparatus for setting up an uplink common bearer in a wireless communication network.
2. Description of the Related Art
The Universal Mobile Telecommunications System (UMTS) refers to a 3rd generation communication system that is based on Global System for Mobile Communications (GSM) and General Packet Radio Services (GPRS), and employs a Wideband Code Division Multiple Access (WCDMA) scheme. The 3rd Generation Partnership Projects (3GPP) responsible for the standardization of UMTS has proposed the Evolved Packet System (EPS) evolution of UMTS, such as the Long Term Evolution (LTE) system. LTE is a technology for implementing high-speed packet-based communication.
FIG. 1 illustrates an architecture of a wireless communication network according to the related art. Referring to FIG. 1, the typical wireless communication network may include a macro enhanced Node B (macro eNB) 102, a Mobility Management Entity (MME) 104, a Serving GateWay (S-GW) 106, a Packet Data Network (PDN) GateWay (P-GW) 108, and a User Equipment (UE) 100.
The macro eNB 102 is a Node B that is in charge of a macro cell. With regard to this, although the macro cell refers to a cell in a typical cellular system, and the macro eNB 102 refers to a Node B for managing and controlling the macro cell, the macro cell and the macro eNB may be used so as to have the same meaning in the present disclosure for convenience in explanation. Therefore, in the following, the macro eNB and the macro cell will be collectively referred to as the macro eNB 102.
The macro eNB 102 is connected to the UE 100 over a radio channel, and controls the radio resources of that connection. For example, the macro eNB 102 may generate control information, which is required within a macro cell, as system information and broadcast the generated system information, or may allocate radio resources in order to transmit/receive data or control information to/from the UE 100. Further, the macro eNB 102 may collect channel measurement result information for a current cell and neighbor cells from the UE 100 to thereby determine if a handover is needed, and may instruct the UE 100 to perform the handover if needed. To this end, the macro eNB 102 is provided with a control protocol for radio resource control, such as a radio resource control protocol.
The MME 104 manages and controls a UE in an idle mode, and selects the S-GW 106 and the P-GW 108. In addition, the MME 104 performs roaming and authentication-related functions. The MME 104 also processes a bearer signal generated in the UE 100.
The S-GW 106 serves as a mobility anchor when a UE is handed over between macro eNBs or moves between 3GPP radio networks.
The P-GW 108 assigns an Internet Protocol (IP) address to the UE 100, performs packet data-related functions of a core network, and serves as a mobility anchor when the UE 100 moves between a 3GPP radio network and a non-3GPP radio network. Further, the P-GW 108 determines a bearer band to be provided to a subscriber, and is responsible for forwarding and routing functions for packet data.
With regard to this, the interface between the macro eNB 102 and the S-GW 106 is referred to as the S1 interface, and the interface between the S-GW 106 and the P-GW 108 is referred to as the S5 interface.
Although not shown in FIG. 1, subscription information according to UEs is stored in a Home Subscriber Server (HSS). When the UE 100 accesses the wireless communication network, the HSS transfers data regarding the UE 100 to the MME 104 so as to enable the MME 104 to use the corresponding data for control of the UE 100.
When the UE 100 is connected to the macro eNB 102, it accesses a data network, such the Internet, by using a data transmission path 110 via the macro eNB 102, the S-GW 106, and the P-GW 108.
FIG. 2 illustrates a bearer setup in which UEs transmit data through uplink bearers for the respective UEs in a wireless communication network according to the related art.
Referring to FIG. 2, the UpLink (UL) bearers for UE 1 to UE 6 200 to 210 are separate bearers that are controlled by the network respectively. In the case of the UL bearer for UE 1 200, for example, the UL radio bearer 222 for UE 1 is connected to the UL S1 bearer 224 for UE 1 at an eNB 212, and the UL S1 bearer 224 for UE 1 is, in turn, connected to a P-GW 218 through the UL S5 bearer 226 for UE 1 that is connected to the UL S1 bearer 224 for UE 1 at an S-GW 216. Consequently, data transmitted by UE 1 200 is transmitted to an IP network 220 via the UL radio bearer 222 for UE 1 (UL radio bearer for each UE)—the eNB 212—the UL S1 bearer 224 for UE 1 (UL S1 bearer for each UE)—the S-GW 216—the UL S5 bearer 226 for UE 1 (UL S5 bearer for each UE)—the P-GW 218. The UL bearers for the other UEs, that is, UE 2 202 to UE 6 210, are also connected to the IP network 220 in the same manner as described for the UL bearer for UE 1.
FIG. 3 illustrates a flow of setting up bearers for respective UEs and transmitting/receiving data through the bearers in a wireless communication network according to the related art.
Referring to FIG. 3, the wireless communication network shown in FIG. 3 includes a UE 300, an eNB 302, an MME 304, an S-GW 306, a P-GW 308, and an HSS 310. First, in step 312, the UE 300 sends an attach request message to the eNB 302. Upon receiving the attach request message, the eNB 302 delivers the attach request message to the MME 304 in step 314. In step 316, the MME 304 sends an update location request message to the HSS 310 to thereby report the identification information of the MME 304 serving the subscriber of the UE 300 to the HSS 310 and simultaneously request the HSS 310 to transfer user subscription data. In step 318, the HSS 310 includes the user subscription data in an update location ACKnowledgment (ACK) message, and delivers the user subscription data to the MME 304 by sending the update location ACK message to the MME 304. In step 320, the MME 304 sends a create bearer request message to the S-GW 306 to thereby request the S-GW 306 to create a new S1 bearer.
In the wireless communication network, the S-GW 306 and the P-GW 308, according to the related art, set up bearers according to UEs through create bearer request and response messages.
That is, upon receiving the create bearer request message from the MME 304, the S-GW 306 sends a create bearer request message, which requests the P-GW 308 to generate a UL S5 bearer, along with DownLink (DL) S5 bearer information (DL S5 info) to the P-GW 308 in step 322. In step 324, the P-GW 308 then sends a create bearer response message, which is in response to the create bearer request message in step 322, along with UL S5 bearer information (UL S5 info) to the S-GW 306. In this way, the UL S5 bearer information and the DL S5 bearer information are shared by both the S-GW 306 and the P-GW 308, and thus it can be said that the S5 bearer for UE 300 has been created.
After the S5 bearer has been created between the S-GW 306 and the P-GW 308, in step 326, the S-GW 306 sends a create bearer response message, which is in response to the create bearer request message for S1 bearer creation in step 320, along with UL S1 bearer information (UL S1 info) to the MME 304. In step 328, the MME 304 then sends a UE context setup request message, which requests the eNB 302 to transfer UE context information (UE context info) required for the eNB 302 to provide service to the UE 300, such as security information and mobility restriction information for the UE 300, along with the UL S1 info to the eNB 302. The eNB 302 performs step 330 (Radio Resource Control (RRC) connection reconfiguration) and step 332 (RRC connection reconfiguration complete) with the UE 300, thereby creating a radio bearer to be used by the UE 300. In step 334, the eNB 302 includes DL S1 bearer information (DL S1 info) in a UE context setup response message that is in response to the UE context setup request message in step 328, and delivers the DL S1 info to the MME 304 by sending the UE context setup response message to the MME 304. The MME 304 sends an update bearer request message including the DL S1 info to the S-GW 306 in step 336, and receives an update bearer response message from the S-GW 306 in step 338, in response to the update bearer request message in step 336. In this way, the UL S1 bearer information and the DL S1 bearer information are shared by both the eNB 302 and the S-GW 306, and thus it can be said that the S1 bearer for UE 300 has been created. Accordingly, in step 340, the UE 300 can transmit data to an IP network via the radio bearer (UL radio bearer for each UE)—the eNB 302—the UL S1 bearer (UL S1 bearer for each UE)—the S-GW 306—the UL S5 bearer (UL S5 bearer for each UE)—the P-GW 308.
As seen from FIGS. 2 and 3, according to the related art, each UE independently maintains its own bearer in the wireless communication network. The same is the case where a small amount of data, such as an alarm message or a power usage result report message, is intermittently transmitted, which causes an unnecessary waste of resources because memory resources, state management resources, and the like to be maintained in an S-GW and a P-GW are too large for transmitted data. Therefore, in order to improve this problem, there is a need for a method and apparatus for setting up bearers such that each UE does not independently maintain its own bearer in a wireless communication network.